1. Field of Invention
The present invention relates to a measuring apparatus, and more particularly to a radioactivity measuring apparatus with a rotating stage for waste drums, which is capable of rotating a sample and applied in contamination measurement for decommissioning wastes.
2. Related Art
Decommissioning wastes contain a large portion of ignorable trace-level radioactive solid wastes, which pose very little threat to the human body or the environment in terms of radioactive hazard. However, these solid wastes are quite a few and take a large proportion in the decommissioning wastes. Therefore, the International Atomic Energy Agency (IAEA) suggests that, the control on trace-level radioactive wastes should be released and these wastes are allowed to be disposed, recycled, or reused like the ordinary wastes. If no related deregulation code is formulated, or no legal release process or radioactive analysis tool is provided, it is impossible to release the control on the wastes, and the wastes must be treated like low-level radioactive wastes. In this case, the disposal cost is rather high, and efforts cannot be concentrated on other more hazardous wastes, which is rather uneconomical.
The waste disposal and deregulation technologies are developed to reduce demands for final treatment of nuclear wastes, and realize the reuse of decommissioning nuclear facilities, which is a major task for each country in decommissioning of nuclear facilities. Therefore, it is rather important to develop and establish an analysis release process and an analysis method for ignorable trace-level solid wastes. Proper detection and categorization of the decommissioning wastes can not only greatly reduce the generation of radioactive wastes to be stored, but also significantly reduce the expenditure and lower the public cost, so that the detection and categorization of the decommissioning wastes are necessary.
In order to achieve stage treatment and security management of the radioactive solid wastes, and greatly reduce the radioactive wastes to be stored, a whole set of decontamination equipment for treating radioactive contamination of metal wastes after disassembly needs to be established. In this equipment, a full solid radioactive waste activity measuring and preliminary screening system plays a rather important role, which is used for measuring a contaminant sample to determine a state of the sample.
FIG. 1A is a schematic view of a radioactive detection device in the conventional measuring system according to the prior art. The radioactive detection device 1 has a case 10. An opening 11 is disposed on a side surface of the case 10. The case 10 has a plurality of planar scintillation detectors 12 disposed therein. In the prior art, a sample 13 with radioactive contamination is to be measured, and the sample 13 is a cylindrical container with contaminant accommodated therein. The container is placed in an accommodating space of the case through complex automatic delivery (as shown in FIG. 1B) or manually for subsequent measurement. In FIG. 1B, the radioactive detection device 1a has a case 10, which is formed by lead shielding plates 100. An opening 101 is disposed on one side of the case 10. An automatic gate 102 is disposed on the opening. An automatic delivery device 14 is disposed on one side of the opening, and used for delivering radioactive waste drums to be measured into the case 10 for subsequent measurement. The conventional automatic delivery device 14 for counting is formed by rollers 16, so as to deliver the waste drums. The case 10 also has rollers 15 to receive and continue to carry the waste drums delivered by the automatic delivery device 14.
Although the conventional radioactive contamination measuring technology can be used to figure out the contamination state of the contaminant in the cylindrical container, it still has the following disadvantages.
1. Firstly, as shown in FIG. 1A, in the prior art, a sample needs to be placed in the case manually and is measured after the gate is shut, which not only wastes manpower but also increases the radioactive dose received by personnel in operation.
2. Further, as shown in FIG. 1B, in the prior art, the rollers 15 and a #-shaped lifting mechanism 17 are disposed in the case, which not only leads to a high mechanical cost but also reduces the measuring efficiency as the detectors below the sample are blocked by the rollers 15 and the lifting mechanism 17.
3. In addition, in the prior art, although the measuring apparatus (as shown in FIGS. 1A and 1B) can be fabricated into a six-surface enclosed structure, but its price rises by multiples with the increase of the width of the detector. As shown in FIG. 1C, generally, a cylinder has a diameter of 60.6 cm, and a conventional detector is 50 cm wide. Since the diameter of the cylinder exceeds the width of the detector, the radiation emitted from areas A1 to A4 cannot be detected by the detectors in all directions, so that the radioactive measurement is underestimated and is thus inaccurate.
4. Even if the position of an intensive radioactive contamination source is detected, as the contamination source may exist at any place in the cylinder, in the case that the contamination source does not exist at a position near the shielding gate, the measuring personnel still need to rotate the cylindrical container manually for easy labeling. As such, the operating process is added, and the operating time is prolonged.
In view of the above, a radioactivity measuring apparatus with a rotating stage for waste drums is needed urgently to solve the problems in the prior art.